Sur la cyclisation des polypeptides

Numerical integration of total vapor pressure-liquid composition curves with the Gibbs-Duhem equation is an established tool for calculating vapor-liquid equilibria of binary systems (1 to 9). The procedure is usually employed with isothermal data, since isobaric data may require accurate values of the heat of mixing. In contrast, it has only rarely been used for multicomponent systems. This is largely explained by the increasing complexity of the calculational procedures and the greater quantity of data required as the number of components is increased beyond 2.Mixon et al. (10) have given a general procedure for isothermal multicomponent total pressure-liquid composition data. It is essentially a generalization of the method of Tao (9) in which nj refers to constant mole numbers for all components except component 1, and + is a correction for gas phase nonideality. The derivatives are taken such that all mole fractions except XI remain in a fixed ratio as XI is varied. It can be shown that this is exact for an ideal liquid phase. Unfortunately, it is not correct for nonideal liquid phases in multicomponent systems, as will be explained later. DEW POINT PRESSURE METHODAll the above methods, both binary and multicomponent, employ bubble point pressures and composition with the Gibbs-Duhem equation for the calculation of the vapor-phase composition. There is no reason, however, why dew point pressures and vapor-phase compositions cannot be used. While the equipment for dew point measurements is more complex, such apparatus have been constructed, and variations could easily be designed.Generally, the sample would be vaporized and the isothermal pressure-volume relations recorded until condensa-R. James is at Massachusetts Institute of Technology. Cambridge, Massachusetts.tion occurred, as noted by a break in the pressure-volume curve; if the pressure rise is rapid as compared with heat transfer, the process will be nearly adiabatic. Then AT/AP = u/CP Since the apparent heat capacity will include the latent heat, it will show a large change at the dew point. An obvious bonus from this procedure would be the byproduct pressure-volume data from which fugacity coefficients could be calculated. The unavailability of the latter is frequently the weakness in the total pressure method. Fortunately, there is also an enormous simplification in the resulting equations as compared with the corresponding liquid-phase calculations. where nj represents %. n3, ---n~. Now

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“…The governing momentum equation is solved by double transformation technique. The solution agrees with that of special case (2).…”

Section: Dew Point Pressure Methodssupporting

confidence: 86%

A method for multicomponent equilibrium calculations by using dew point pressure‐vapor composition data

Davison¹,

James²,

Tromblee³

1970

AIChE Journal

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“…Structural studies show the presence of 3-and 4-linked j?-D-glucopyranosyl units in the ratio 3:7 (77)(78)(79)129,130). It was described in 1815 (128) and can be purified by solubilization in hot water followed by collection of the precipitate that forms on cooling.…”

Section: Linear /?-D-glucopyranans With (1-*3) and (1->4) Linkagesmentioning

confidence: 99%

The Chemistry of Polysaccharides of Fungi and Lichens

Gorin¹,

Barreto‐Bergter²

1983

The Polysaccharides

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“…It is known that carboxylic acids can react with chloroformates in the presence of a basic catalyst to give carbonic carboxylic anhydride. The aminolysis of the anhydride groups formed gives the expected amides with the formation of carbonic anhydride 25–27. The synthesis of amide derivatives of VP‐TBMA‐MAA terpolymers ( R ‐COOH) was accomplished as shown in Scheme .…”

Section: Resultsmentioning

confidence: 99%

Synthesis and characterization of N‐vinylpyrrolidone‐tert‐butyl methacrylate‐methacrylic acid terpolymers having amino sugar or bioactive amino side compounds

Martínez

Sánchez‐Chaves

2004

J. Polym. Sci. A Polym. Chem.

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Free‐radical copolymerization of N‐vinylpyrrolidone (VP) with tert‐butyl methacrylate (TBMA) was carried out in bulk at 50 °C, using 2,2′‐azobisisobutyronitrile as initiator. From copolymer composition determined by 1H‐NMR analysis and using the modified Kelen–Tüdos equation, the monomer reactivity ratios were determined. After acidic hydrolysis, the modification reaction of some N‐vinylpyrrolidone‐tert‐butyl methacrylate‐methacrylic acid (VP‐TBMA‐MAA) terpolymers with several model bioactive amino compounds (benzocaine, phenethylamine, tyramine) and a model amino sugar (2‐amino‐2‐deoxy‐D‐glucose (glucosamine)) was studied in the homogeneous phase. Interaction experiments between glucosamine‐carrying VP‐TBMA‐MAA terpolymers and Concanavalin A (Con A) in a phosphate buffer (pH = 7.2) at room temperature showed that VP‐TBMA‐MAA terpolymer interacts with Con A. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 18–27, 2005

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Sur la cyclisation des polypeptides

Abstract: A method for the cyclisation of linear neutral peptides has been elaborated. D‐leucyl‐glycyl‐glycine has been cyclised into cyclo‐D‐leucyl‐glycyl‐glycyl with a 37% yield.

Cited by 69 publications

References 15 publications

A method for multicomponent equilibrium calculations by using dew point pressure‐vapor composition data

A method for multicomponent equilibrium calculations by using dew point pressure‐vapor composition data

The Chemistry of Polysaccharides of Fungi and Lichens

Synthesis and characterization of N‐vinylpyrrolidone‐tert‐butyl methacrylate‐methacrylic acid terpolymers having amino sugar or bioactive amino side compounds

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